BRITISH HETER(ECIOUS UREDINES. 93 
the former not. Conversely, P. Caricis from C. hirta gave rise 
to the Zeidium Urtice, but not tothe ZEcidium on Centaurea. 
It was thus conclusively demonstrated that P. arenariicola 
is distinct from both P. Caricis and P. Scheleriana. 
Subjoined is a tabular summary of the cultures made, the 
duplicated experiments being bracketed together :— 
PUCCINIA ARENARIICOLA. 
No. Infecting material. Plant infected. i Dato of Date of first 
466. Puccinia arenariicola.| Centaurea nigra. 81 March | 21 April 
477. » » » " 8 April | 18 April 
478. ” ” ” ” ” ” 
479. 39 39 39 „ ” „ 
480. 39 ” ” ” 2 LU 
530. ” ” ” ” 12 May 29 May 
633. » » » » 24 May 6 June 
529. ZEcidium Centaurie. | Carex arenaria. 12 May | 29 May 
537. » » » » 15 May 6 June 
501. } Puccinia Scheleriana.| Senecio Jacobea. 25 April | 11 May 
502. | » » Centaurea nigra. » —— 
447. » " Senecio Jacobea. 15 Sept. | 26 Sept. 
447* ! » » Centaurea nigra. » — 
467. Puccinia arenariicola. " » 8 April | 18 April 
468. » » Senecio Jacobea. » — 
508. | | Puccinia Caricis. Centaurea nigra. 1 May 
509. } » » Urtica dioica. " 18 May 
531. Puccinia arenariicola,| Centaurea nigra. 12 May 29 May 
532. } » » Urtica dioica. » = 
THE GYMNOSPORANGIA. 
It has hitherto been generally accepted that in Europe we have 
three species of Gymnosporangium which have their three corre- 
sponding ecidiospores or Ræsteliæ, namely :— 
1. G. clavarieforme = R. lacerata, on Crataegus Oxyacantha. 
2. G. juniperinum = R. cornuta, on Pyrus Aucuparia. 
8. G. fuscum = R. cancellata, on Pyrus communis. 
In May 1882, however, some cultures were made with these 
Gymnosporangia which gave certain unexpected results, inasmuch 
as they showed that the æcidiospores were not confined to the 
three host-plants above named. It was found that G. clavariæ- 
Jorme was capable of producing æcidiospores on Pyrus communis 
as well as upon Crategus Ozyacantha, and that G. Sabine could 
give rise to a Restelia on Crategus Oxyacantha as well as upon 
Pyrus communis. The life-history of the @ymnosporangia there- 
fore is not so simple a matter as the experiments of (Ersted would 
LINN. JOURN.—BOTANY, VOL. XXIV. I 
